NumPy Logic functions: isnan() function

Last update on August 19 2022 21:51:10 (UTC/GMT +8 hours)

numpy.isnan() function

The isnan() function is used to test element-wise for NaN and return result as a boolean array.

Syntax:

numpy.isnan(x, /, out=None, *, where=True, casting='same_kind', order='K', dtype=None, subok=True[, signature, extobj]) = <ufunc 'isnan'>

Version: 1.15.0

Parameter:

Name	Description	Required / Optional
x	Input array. array_like	Required
out	A location into which the result is stored. If provided, it must have a shape that the inputs broadcast to. If not provided or None, a freshly-allocated array is returned. A tuple (possible only as a keyword argument) must have length equal to the number of outputs. ndarray, None, or tuple of ndarray and None	Optional
where	Values of True indicate to calculate the ufunc at that position, values of False indicate to leave the value in the output alone. array_like	Optional
**kwargs	For other keyword-only arguments	Required

Returns:
y : ndarray or bool - True where x is NaN, false otherwise. This is a scalar if x is a scalar.

Notes:
NumPy uses the IEEE Standard for Binary Floating-Point for Arithmetic (IEEE 754).
This means that Not a Number is not equivalent to infinity.

NumPy.isnan() method Example-1:

>>> import numpy as np
>>> np.isnan(np.nan)

Output:

True

NumPy.isnan() method Example-2:

>>> import numpy as np
>>> np.isnan(np.inf)

Output:

False

NumPy.isnan() method Example-3:

>>> import numpy as np
>>> np.isnan([np.log(-2.),2.,np.log(0)])

Output:

array([ True, False, False])

Python - NumPy Code Editor:

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